SPECIFIC AIMS 1. To compare the effect of oral hypoglycemic agents Glipizide-GITS and Metformin alone or in combination on hepatic glucose production in patients with NIDDM. 2. To compare insulin secretory responses to Sustacal in patients with NIDDM receiving Glipizide-GITS or Metformin alone or in combination. It is the hypothesis of this proposal that the combination of an oral hypoglycemic agent that improves insulin secretion (Glipizide) with one that improves insulin action (Metformin) in the treatment regiment of NIDDM patients will provide improved glycemia compared to either agent alone through a synergistic effect on insulin secretion and action.